Field of the Disclosure
The disclosure relates to a pixel structure and a fabricating method thereof.
Description of Related Art
In various flat panel displays, thin film transistor liquid crystal displays (TFT-LCDs) are very popular due to the advantages of high space utilization rate, low power consumption, non-radiation, low electromagnetic interference, and so forth. The TFT-LCD is generally composed of an active array substrate, a color filter substrate, and a liquid crystal layer sandwiched between the two substrates. The active array substrate has an active region and a peripheral circuit region. The active array is located within the active region, and the driving circuit is located within the peripheral circuit region.
In the active array of the active region, for instance, thin film transistors (TFTs) with a high channel width-to-length (W/L) ratio are often used. In general, a turned-on current (Ion) of the TFT is in direct proportion to the W/L ratio and satisfies the following equation: Ion=U*W/L*(VG−Vth)*VD, where U is carrier mobility, W is channel width, L is channel length, VG is gate voltage, Vth is threshold voltage, and VD is drain voltage. It can be derived from the above equation that the turned-on current (Ion) can be increased by increasing the W/L ratio. However, subject to the feasible exposure and development techniques at present, the channel length can be merely reduced to approximately 3.5 μm.
To effectively increase the W/L ratio, the conventional issue provided above may be alternatively resolved by increasing the channel width. Nevertheless, the increase in the channel width often leads to the significant increase in the layout area of the device, which results in the loss of the aperture ratio.